Cardiovascular and metabolic response to dynamic stress echocardiography by patients with coronary heart disease and healthy probands

Abstract

25 patients with coronary heart disease (CHD, 62 +/- 9 years) and 18 subjects free from cardiovascular disease (28 +/- 9 years) were tested on a cycle ergometer using a graded incremental test protocol: a) in the common upright position, b) as dynamic stress echocardiography in a semi-supine position. Whereas no relevant differences could be detected between the two conditions for the healthy subjects concerning heart rate, blood pressure, and rate-pressure product (2 x 3 ANOVA, t-tests with alpha-adjustment), the CHD patients showed both significantly higher heart rates as well as a significantly higher rate-pressure product (50 W: 15,300 +/- 2973 mm Hg/min vs. 13,822 +/- 3042 mm Hg/min; 75 W: 18,028 +/- 3479 mm Hg/min vs. 16,337 +/- 2619 mm Hg/min) on equivalent stages during stress echocardiography if compared to the sitting position. There were no differences for systolic blood pressure in this group; the diastolic values were higher in the sitting position at rest and during 50 W. Lactate concentrations (determined only in the healthy subjects) were significantly higher on all stages during dynamic stress echocardiography. The workload at the individual anaerobic threshold (IAT) was significantly lower. In conclusion, we found a higher metabolic along with a similar cardiovascular strain at equivalent workloads in stress echocardiography compared to upright bicycle ergometry for healthy subjects. However, CHD patients have a higher cardiocirculatory load in the semi-supine position. When investigating these patients with stress echocardiography, higher heart rates of about 8 beats/min have to be expected for equivalent workloads if compared to the upright position.